Taking place in the midwest, Fallout Tactics is about the Brotherhood of Steel fighting through an army of hostile robots to get to Vault 0, a vault located in the mountains.

The story starts with the player character joining the Brotherhood of Steel as an initiate. Shortly after, war between the BoS and a new faction named the Beast Lords break out. The Beast Lords can control animals (such as mirelurk's and deathclaw's) with their mind.

The Brotherhood prevails, and go back to pursuing new technology. However, the brotherhood discovers an army of robots sweeping in from the west. The Brotherhood is outnumbered, and it's up to you and your companions to break into Vault Zero, and destroy the leader of the robots, the Calculator.